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Ch. 2 - Functions and Graphs
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Not the one you use?Change textbook
Chapter 3, Problem 36a

Find f+gf+g, fgf-g, fgfg, and fg\(\frac{f}{g}\). Determine the domain for each function.
f(x)=6x2x1f\(\left\)(x\(\right\))=6x^2-x-1, g(x)=x1g\(\left\)(x\(\right\))=x-1

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Step 1: Understand the problem. You are tasked with finding the domain of the functions f(x) = 6x^2 - x - 1 and g(x) = x - 1, as well as the domain of their combinations: f + g, f - g, fg, and f/g. The domain of a function is the set of all x-values for which the function is defined.
Step 2: Analyze the domain of f(x). Since f(x) = 6x^2 - x - 1 is a polynomial, it is defined for all real numbers. Therefore, the domain of f(x) is all real numbers.
Step 3: Analyze the domain of g(x). The function g(x) = x - 1 is also a polynomial, so it is defined for all real numbers. Thus, the domain of g(x) is all real numbers.
Step 4: Determine the domain of f + g, f - g, and fg. Since these operations involve adding, subtracting, or multiplying two polynomials, the resulting functions are also polynomials. Therefore, the domain of f + g, f - g, and fg is all real numbers.
Step 5: Determine the domain of f/g. Division by zero is undefined, so we must exclude any x-values that make g(x) = 0. Solve g(x) = x - 1 = 0, which gives x = 1. Therefore, the domain of f/g is all real numbers except x = 1.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Function Operations

Function operations involve combining two or more functions through addition, subtraction, multiplication, or division. For example, if f(x) and g(x) are two functions, their sum is defined as (f + g)(x) = f(x) + g(x). Understanding these operations is crucial for manipulating and analyzing functions in algebra.
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Domain of a Function

The domain of a function is the set of all possible input values (x-values) for which the function is defined. For polynomial functions, like f(x) = 6x² - x - 1, the domain is all real numbers. However, for rational functions, such as g(x) = x - 1, the domain must exclude values that make the denominator zero.
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Rational Functions

Rational functions are ratios of two polynomials, expressed as f(x) = P(x)/Q(x), where P and Q are polynomials. The domain of a rational function is determined by identifying values that make the denominator zero, as these values are undefined. Understanding how to find the domain of rational functions is essential for solving problems involving function operations.
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